SEOUL, April 24 (Yonhap) -- South Korea's financial regulators said Wednesday they have launched an all-out overhaul on network security systems at major financial companies in a bid to prevent them from being exposed to cyber attacks that may result in a serious breach of private data.

The Financial Supervisory Service (FSS), the country's financial watchdog, and its superior body the Financial Services Commission (FSC) said they have been working to toughen rules in online network systems at banks, insurers and other companies. They plan to unveil a comprehensive measure in June.

The authorities are focused this time on stiffening measures to an extent that chief executives will legally be held accountable for any failure in online security systems and be rebuked for negligence, the FSC said.

The watchdogs' move marks an unprecedented overhaul in network security at financial companies here, which came as a spate of the latest cyber attacks on some banks and insurers' online network stoked strong criticism and concerns over the safety of personal data storage on the Internet.

The lax online security emerged as a major problem in the local financial market since Web pages of two local banks and two insurers were hacked last month by unknown malware suspected of having come from North Korea, halting their online networks and causing inconveniences for online bank users. There was no leakage of personal information.

On Tuesday, online banking was again under fire after a twitter user claiming to be a member of the international hacking group Anonymous disclosed personal data he claimed to have stolen from No. 5 lender Korea Exchange Bank Web server.

An FSS official said the regulator plans to complete the all-out overhaul by mid-May before it reports its findings to the FSC. Detailed results on the investigation will be released around the beginning of the second half of the year, and those responsible will face severe consequences, he added.

According to local law, a financial company must assign 5 percent of its staff to the IT department, of which 5 percent must be assigned with security tasks. The firm also has to spend 7 percent of its budget on online security networks. But regulators suspect that such rules have hardly been applied, largely due to heavy costs for setting up facilities.